I have a question about -- prefix. It subtracts 1 from the variable, but when I put --sub_total for a new variable (newsub=--sub_total), it subtracts 1 for newsub and my sub_total also. Why does it do this? When I take the line newsub=--sub_total, my sub_total is good, and as soon as I introduce a --prefix in another equation, it affects the original sub_total too. Help appreciated!

The prefix minus decrements the variable and then the variable's (new) value is used in the rest of the statement. subTotal = 10; newsub = --subTotal; subTotal is decremented to 9 and then the new value of subTotal (9) is assigned to newsub. So both newsub and subTotal will be 9. The postfix minus will use the value of the variable in the statement and then decrement the variable. subTotal = 10; newsub = subTotal--; The value of subTotal (10) is assigned to newsub and then subTotal is decremented. So, newsub will be 10 and subTotal 9. Hope this helps.

Thank you for the reply. What if I don't want to decrement subTotal, but only decrement newsub by 1 using subTotal, can this method still be used? In other words, in both of your examples, subTotal is decremented, can subnew be the only one decremented, and can you leave subTotal the same using this method?

I've found a way how to do it, no need to worry about it.